The invention relates to a method and device for manufacturing intermediate products for preparation of animal feeds.
Raw materials for animal feeds, such as for instance soya beans, often contain so-called anti-nutritional factors which have an adverse effect on the nutritional value of the raw material. In order to eliminate such factors, the raw materials are subjected to a heating process, so-called "toasting". Herein the raw materials are heated to a minimum of 100.degree. C. by means of direct steam injection in a toaster. The same method is also used for instance in the opening up of cereals, peas and fodder beans, whereby the nutritional value of the raw materials is improved. After the treatment the raw materials, if required following a final processing, are dried with partially pre-heated air. They are then cooled by means of cold air and optionally subjected to a second after-treatment to obtain the intermediate products. The air from the cooler and the dryer disappears to the outside via cyclones. A significant amount of energy and moisture is lost herein.
It is therefore important to recover the greatest possible amount of energy. According to the customary methods energy is recovered by means of porous link or belt conveyors on which the product lies and through which a large amount of air is blown. The air absorbs the heat from the product and its temperature becomes the mean temperature of the inblown air and the product. The consequence is that no optimum heat transfer takes place. An additional problem is that the air speeds are so great that large quantities of product and dust are carried along therewith. The air hereby becomes unsuitable for re-use.